Water Rocket Forum

Welcome to the Water Rocket Forum, sponsored by The Water Rocket Achievement World Record Association.

The largest, most sophisticated and ground breaking group supporting you, the serious water rocket flyer! Whether you are a beginner or an expert, the WRA2 has something for everyone.

A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

About a year ago we came up with a list of experiments we wanted to document using regular water rockets that anyone could build and fly, but we felt that a lot of people were reluctant to risk flying anything that costs more than say $5.00 because they did not trust any recovery system to work reliably.

We decided that we needed to find out what people were thinking, so we formed a focus group of students who were given the task of finding plans for a parachute system, building it, and then flying it. At the end of the focus group we had them fill out a survey to discuss what they did and how it could be improved. The results were very interesting.

Every participant of our group managed to find plans online for similar "Side" deploy systems, which appear to all be based on the "Horizontal Deploy" that Robert Youens developed over 10 years ago. They all operated on the same principal, and differed only in materials and subtle changes in assembly that appear to merely be the plan author attempting to personalize the existing designs and make them his or her own "unique" system. This style recovery system has a compartment to hold the chute built from common sheet material or wood, and a trap door on the side of a bottle with an ejector spring made from a bottle or rubber bands to push the chute out.

Old_School_Side_Deploy.jpg

The focus group had a number of issues with the traditional design:
1) It is made from 16-20 custom made pieces.
2) All pieces must be built to tight tolerances to fit together and work.
3) The system can only be attached to the rocket at the top where it is most likely to be damaged in a crash.
4) 3-5 moving parts must work correctly or the deploy will fail.
5) There are numerous places where the chute can pinch or snag.
6) Assembly takes a very long time with some plans having 55-65 discrete steps.
7) Damage from a crash can make repairs difficult or impossible.

With this all in mind, we took a look at the current "state of the art" and decided that not enough work has been done in this field in spite of a surge in popularity of water rockets. We felt that coming up with a new system that solved all of these issues would be a great project.

The first brainstorm we had was to replace the hinged trap door and ejector plate with a parachute cover that would be forcefully flung open thanks to the centripetal force of the rubber band used to hold it closed. The force of the unwrapping rubber band is applied radially around the central axis of the rocket, giving the system a feature that was new and unique.

Once the radial actuation idea was proven to work, we realized that the meticulously built internal compartment and doorway could also be totally eliminated if the parachute cover was simply not cut so small. We could use the neck area surrounding a tornado tube to house the parachute. We could also recreate the same neck area using an extra bottle taped to the top of the rocket. This means the system can mount anywhere on the rocket.

Having gotten rid of all those tricky to make parts, we reduced the complexity and time to build the system. This met all of the requirements we set out to meet.

USWR_Radial_Deploy.jpg

The new system has the following improvements:

1A) It is made from only 2-3 custom made pieces.
1B) The remaining 2-3 pieces are all used in unmodified form with no alterations needed.
2) No tight tolerance parts need to be made.
3) The system can be attached to different locations on the rocket, possibly preventing damage in a crash.
4) Only 1 moving parts must work correctly.
5) Eliminated all places where the chute can pinch or snag.
6) Assembly takes a very short time, having only 8 simple steps.
7) Damage from an unlikely crash is no big deal.

We are pleased to share the idea for this deploy system with the community. Please visit the tutorial on our website to see how to make your very own version, or watch the video link at the bottom of the tutorial page to see it in action!

Here's my take on it using a tomy timer for the release mech. I think it took longer to watch the video than to install the clockworks.

I melted 4 holes in the coroplast to run 2 zipties. I also applied a little hotmelt around the perimeter to lock it in place.

To activate the timer, I installed a carbon arrow shaft on my launcher. The arrow shaft is friction fit so I can adjust it up and down as needed. The wood dowel installed on the end of the winder slides into the arrow shaft and is held in place until launch.

Time delay is acheived by winding the rubber band with the timer. The installed timer has a max delay of about 4 seconds. The previous flight of this pressure vessel reach apogee in 3 seconds so I think I'm pretty well matched.

I added a ziptie loop to the rubber band for attaching to the winder. This helps it slide off since the rubber grips the wood too well.

I installed a 360 deg camera on the back side of the coroplast payload sled.

Way too windy to launch right now. Hope it subsides this evening. In the meantime, here's a test deployment

[youtube][/youtube]

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You're the fastest person who saw our video on YouTube to try their own hand at building the new style deploy system! And it worked great right out of the gate! That's a pretty good testimonial!

Thanks! I think it speaks volumes to the simplicity and adaptibility of the design. I already have a Servochron nosecone built up as well, just waiting to get a new soldering iron to finish the board connections.

So i finally had a failure using this deployment system. It's easily preventable so I thought I'd share here.

After my last flight, I decided I'd replace the rubber band (it was over a year old and had been used previously on airplanes) so I stored the rocket loaded.

A preflight check yesterday showed that the PET wrap had curled and assumed its new shape. I reverse rolled it thinking it might be enough. It wasn't. When the timer released the rubber band at apogee, the PET wrap stayed curled loosely around the rocket and didn't release the parachute. Lawn dart. Luckily, no damage.

So lesson of the day- keep the pet wrap loose or flat when storing, otherwise cut a new one.

bugwubber wrote:So i finally had a failure using this deployment system. It's easily preventable so I thought I'd share here.

After my last flight, I decided I'd replace the rubber band (it was over a year old and had been used previously on airplanes) so I stored the rocket loaded.

A preflight check yesterday showed that the PET wrap had curled and assumed its new shape. I reverse rolled it thinking it might be enough. It wasn't. When the timer released the rubber band at apogee, the PET wrap stayed curled loosely around the rocket and didn't release the parachute. Lawn dart. Luckily, no damage.

So lesson of the day- keep the pet wrap loose or flat when storing, otherwise cut a new one.

You may find that if you leave the rubber band wrapped in the armed position that in a few weeks it will become permanently stretched like that. There are some expensive rubber bands made of different rubbers that tend to not do this, and they are also immune to UV and oxidation. They are made for long term storage of tiems so they don't fall apart a few years later.

bugwubber wrote:So i finally had a failure using this deployment system. It's easily preventable so I thought I'd share here.

After my last flight, I decided I'd replace the rubber band (it was over a year old and had been used previously on airplanes) so I stored the rocket loaded.

A preflight check yesterday showed that the PET wrap had curled and assumed its new shape. I reverse rolled it thinking it might be enough. It wasn't. When the timer released the rubber band at apogee, the PET wrap stayed curled loosely around the rocket and didn't release the parachute. Lawn dart. Luckily, no damage.

So lesson of the day- keep the pet wrap loose or flat when storing, otherwise cut a new one.

You may find that if you leave the rubber band wrapped in the armed position that in a few weeks it will become permanently stretched like that. There are some expensive rubber bands made of different rubbers that tend to not do this, and they are also immune to UV and oxidation. They are made for long term storage of tiems so they don't fall apart a few years later.

Funny side note- the used rubber band that I decided to replace, I tried to break it by pulling it apart. It is still in one piece. This is FAI Tan Sport 3/32" rubber.

I spray down the rubber with 303 Aerospace Protectant. Both for lubrication and SPF.

bugwubber wrote:So i finally had a failure using this deployment system. It's easily preventable so I thought I'd share here.

After my last flight, I decided I'd replace the rubber band (it was over a year old and had been used previously on airplanes) so I stored the rocket loaded.

A preflight check yesterday showed that the PET wrap had curled and assumed its new shape. I reverse rolled it thinking it might be enough. It wasn't. When the timer released the rubber band at apogee, the PET wrap stayed curled loosely around the rocket and didn't release the parachute. Lawn dart. Luckily, no damage.

So lesson of the day- keep the pet wrap loose or flat when storing, otherwise cut a new one.

You may find that if you leave the rubber band wrapped in the armed position that in a few weeks it will become permanently stretched like that. There are some expensive rubber bands made of different rubbers that tend to not do this, and they are also immune to UV and oxidation. They are made for long term storage of tiems so they don't fall apart a few years later.

Funny side note- the used rubber band that I decided to replace, I tried to break it by pulling it apart. It is still in one piece. This is FAI Tan Sport 3/32" rubber.

I spray down the rubber with 303 Aerospace Protectant. Both for lubrication and SPF.